Conventional structures of control units for movable axes on program-controlled machines, especially in the case of industrial robots, are intended to move along a programmed path as accurately as possible, regardless of the load. The control units currently available are unable to respond in the desired manner to deviations or obstacles occurring in reality by yielding. To circumvent the problems, mechanical flexibilities and/or expensive, monitoring devices must be installed in the robots. This requires extra efforts in terms of design and programming, as well as extra costs.